In the oil industry, chemical industry and other fields of industry phase separation is widely used. Generally, liquid and gaseous components of a mixture are separated in separators operating with overpressure. Known separators are arranged partly in vertical or in horizontal position. In continuous operation of separators the separated phases should be led away continuously, suitably by maintaining liquid level and pressure at constant levels. For that purpose regulators are installed into the outlets of the liquid and gaseous phases. Regulating sensors can be moved by direct mechanical arrangement, or by an interior converter utilizing auxiliary energy.
Generally the two tasks, namely the regulation of pressure, and the control of liquid level are carried out by two independent units.
In mechanical pressure regulation a valve, usually a butterfly valve, is arranged in the gas outlet, moved suitably by a float sensing the liquid level. The application of such constructions is rather restricted due to the required considerable moving forces. Due to these considerable forces, neither catches, nor slide valves are used for direct regulation of liquid levels.
A solution is also known, in which regulation is performed by a balanced rotating slide valve installed into the liquid outlet of the separator. A properly dimensioned float can turn the slide valve.
Mechanical liquid level and pressure regulators are disclosed in the book "Sbor, Transport I Podgotovka Nefti" (Nedra Edition, Moscow, U.S.S.R., 1975). FIG. 48, page 122 shows a mechanism comprising a float connected through rigid shafts to two butterfly valves in the liquid and gas outlet conduits each for controlling the liquid level of the separator.
A drawback of this solution is that the forces needed for moving the butterfly valves are considerably high and that the value of the forces depends on the angle position of the butterfly valves and on the value of the measured yield. The float must be dimensioned to accommodate the maximum torque. The required torque is increased by friction forces on the block casings of the outlet subs of the butterfly valves and on the shafts of the moving mechanism. The above solution can be used only infrequently due to those drawbacks.
FIG. 35, page 96-97, of the same book shows a similar mechanism which is often employed. That mechanism includes a butterfly valve in the gas delivering outlet. The drawback of this structure is that the discharge of the separator cannot be eliminated.
No mechanical construction is known which provides a simultaneous regulating of liquid level and of pressure of separators, without utilizing external power input.
The fundamental drawbacks of the known mechanical regulating systems are that the restricted actuating force produced by them is generally not suitable for the actuation of the control organs, and also synchronization of the level and the pressure regulation have not been accomplished as yet.
Regulators actuated by auxiliary energy have been applied to eliminate these drawbacks, but a disadvantage of this is that they also require auxiliary power.